The present invention relates to a traffic crash attenuation system. More particularly, the present invention includes a system, method and apparatus for absorbing the kinetic energy from an impacting vehicle in a controlled and safe manner with roadside safety devices such as: guardrails and median barrier end treatments, crash cushions, and truck mounted attenuators. Specifically, the present invention provides a system for the controlled rupturing of a tubular member by a mandrel whereby forces of an impacting vehicle are absorbed. More particularly, the present inventive system utilizes a rectangular mandrel and a corresponding rectangular tubular member.
U.S. Pat. No. 4,200,310 illustrates an energy absorbing system which utilizes a number of cylindrical energy absorbing members placed in a series-type relationship on a frame mounted to a truck. The system is provided with an alignment or guidance frame. However, there is nothing, which teaches any selectively controlling the rupture of the cylindrical members. The mechanism of energy dissipation is significantly different than that of the present invention.
U.S. Pat. No. 3,143,321, teaches the use of a frangible tube for energy dissipation. As with the present invention, the apparatus disclosed in U.S. Pat. No. 3,143,321 uses a mandrel receivable within a tubular member. However, there is no teaching of a means for selectively controlling the rupturing along a length of the tubular member.
The crash attenuation system of the present invention provides an impact head attached to an energy absorption mechanism. The energy absorption mechanism has one or more mandrels with a certain tensile strength or hardness attached to the impact head. Attached to the head are one or more tubular members which have second tensile strengths or hardnesses, generally lower than those of the mandrels. The mandrels are receivable in a first end of the tubular members such that upon impact forces being applied to the impact head, the mandrels are forced through the tubular members rupturing, rather than fragmenting, the tubular members and absorbing the impact forces. The rupturing may be controlled by any number or combination of stress concentrating elements such as placing holes, notches, cuts, scores, preferential material orientation, or slots in the tubular members, providing gussets (or any strengthening member) along the length of the tubular members, or providing the mandrels with stress concentrators such as gussets or mandrel geometry so that as the mandrels are urged through the tube the rupturing is controlled. Specifically, the present invention focuses on rectangular mandrel and rupture tube geometry.
FIG. 1A is an isometric view of a mandrel and tubular member of the present invention before impact forces are applied.
FIG. 1B illustrates the rupturing of the tubular member by the mandrel upon impact.
FIG. 2A is a side elevation view of an embodiment of the present invention having a mandrel with a forward tubular extension and a tubular member with a second mandrel.
FIG. 2B is an end view of the illustration of FIG. 2A.
FIG. 2C is a side elevation view of an embodiment of the present invention with the first and second mandrels having stress concentrators.
FIG. 2D is an end view of the illustration of FIG. 2C.
FIG. 3A shows a top plan view of the present invention with the controlled fracture energy absorbers attached to the impact head and trailer or truck mounted frame elements.
FIG. 3B is a side elevation view of the illustration of FIG. 3A.
FIG. 4A shows a top plan view of the present invention with an alignment member attached to the trailer or truck mounted frame.
FIG. 4B is a side elevation view of the illustration of FIG. 3C.
FIG. 5A illustrates the rectangular mandrel of the present invention.
FIG. 5B shows the rectangular tubular member of the present invention.